For a time the complex - consisting of churches, barracks, the Governor's residence, enclosed in 6-meter-high walls - was Manila itself, with the Spanish elite and the mestizos as its residents. Moats were added in 1610 to give the city more protection from pirate attacks. Two old churches that still stand today - San Agustin church and the Manila Cathedral - are within its walls.
A garrison - Fuerte de Santiago, originally built in the same year but destroyed in a war - was rebuilt in 1589 as a stone fort, with 8-foot thick walls. This is where Jose Rizal, the national hero, was held prior to his execution in 1896.
Walking along its cobblestoned streets is a nice way to relive a bygone era. Hiring a calesa would make the tour a bit more interesting too.
How to Get There: take a jeepney to the city hall of Manila, take the underpass to the other side to reach the entrance. If via LRT, get off in UN Avenue station then take a stroll to the gate. Alternatively, you may get off Carriedo station and take a jeepney from Chinatown to the gate of the complex.